Earthquake activity in Alaska is concentrated along the boundary between the Pacific Plate and the North America continent, as well as in the interior of Alaska where tectonic stresses are translated from the plate boundary. Earthquakes of large magnitude occur at depth along the Aleutian Megathrust; the fault surface on which the Pacific Plate slides beneath Alaska as it is subducted into the earth’s mantle. Earthquakes of small to large magnitude are also distributed throughout southeastern, southcentral, interior, and northern Alaska at shallower depths within the crust. This crustal earthquake activity is concentrated along several major faults that allow for the displacement of segments of the crust being pushed into southern Alaska by the collision with the Pacific Plate.
A number of major earthquakes have occurred in Alaska since recording of seismic signals began in the late 19th and early 20th century. Among these events are the Great Alaskan Earthquake of 1964 which occurred at depth on the Aleutian Megathrust beneath southcentral Alaska, and the Denali Fault Earthquake of 2002 that occurred in the crust of interior Alaska along a major strike slip fault.